Equinus

With the subtalar joint in neutral position, an equinus foot has less than 10 degrees of ankle Dorsiflexion.

This deformity occurs when an inadequate amount of ankle joint dorsiflexion is present. When this exists, compensation occurs with subtalar joint pronation, which subsequently unlocks the midtarsal joint, collapsing in the midfoot. The foot then cannot function normally in propulsion. With locomotion and the momentum of the leg lifting the heel, the midfoot collapses causing a ‘rocker bottom’ type effect. In any case, something’s got to give, in order for the leg, hips and pelvis to continue forward in locomotion.